1. Field of the Invention
The present invention relates to a milling cutter body and a process for the production of this milling cutter body.
2. Description of Related Art
A typical milling cutter tool comprises a holder that can be fixed at the end of a rotating shaft in a predetermined relationship to its rotation axis, and a cutting edge which is carried by the holder at a radial distance from the axis of rotation on the side of the holder that is distal from the shaft, so that the cutting edge describes a circle around the central axis of the shaft when the body is rotated by the shaft. All parts of the holder are located axially and radially behind the cutting edge, so that it may freely come into contact with and machine the surface of a workpiece, which is held in the machine in which the shaft rotates. Since the separate cutting edge is relatively short, it performs a relatively narrow cutting process, wherefore the tool is used with a cross feed or table feed, the direction of feed being parallel to the machined surface of the workpiece, or has an angle to said surface. The cutting edges as such are usually located on detachably fastened cutting inserts, which are usually indexable cutting inserts with one or several cutting edges, or also round inserts.
When milling with face milling cutter bodies, one makes a distinction between a one-tooth cutter, a coarse pitch cutter and a close pitch curter, which have different fields of utilization. The one-tooth cutter, which is mounted in a built-in element, is finely adjustable, i.e., the main cutting insert, which is convexly shaped, can be adjusted in relation with the working plane, it being possible also to compensate for the inclination of the spindle by this fine adjustment.
Coarse pitch cutters are provided with cassettes which accomodate round or square indexable cutting inserts. They are usually utilized for so called rough milling whereby the attained surface quality depends on the feed per tooth of the utilized indexable cutting insert and the axial planar feed of the miller. Normally, R.sub.a -values between 3.2 and 12.5 .mu.m are obtained.
Close pitch cutters are primarily used in the motor industry. They are suited for the milling of cylinder blocks and similar parts.
When milling profiles, full-width grooves, continuous ramping with helical interpolation and pockets by ramping, then cutting inserts with round edges are suitably used. Similar to other cutting edges, each one of the rounded inserts can be fastened by a locking screw, which is threaded through a central through-hole in the cutting insert and is tightened into a threaded hole in the milling cutter body. Such a milling tool is disclosed in DE-U-93 05518.8.
In order to make possible a high table feed, and thereby a high productivity, it is necessary to have stable machines and motors with a high output. If these two basic conditions are fulfilled, then naturally a close pitch cutter gives a higher table feed than a coarse pitch cutter, if the tooth feed is of the same order of magnitude in the two cases. Moreover, it is a well-known fact for the skilled man that at a given table feed, a close pitch cutter gives a smoother surface than a coarse pitch cutter.